Each line is a concept of a team. Having not play-tested either team, does anyone have ideas on how to make these teams as even as possible? Or having experience demonstrating Dice Masters or another game, should I give the participant an advantage? A disadvantage?

In addition, I have the following dice that I intend to use for prizes:

I aim to distribute 8 cards and the corresponding die to each participant who can beat me. Further I will award a Professor X: Recruiting Young Mutants to those participants who can beat me in either under 10 minutes or by 10 points...(qualifications to be determined). I have two copies of PXG available.

If anyone has any ideas or experience demonstrating Dice Masters I'd love to hear your comments.

Actually really like the balance of things, but I think there's a little bit that I'd swap around for some fine tuning and thematic purposes.

I think you should swap in Apocalypse from your prizes for Marvel Girl (since her effect is mediocre and the team lacks a beatstick) and give Cable to team 1 in exchange for Magik (you could also switch in Pyro - Saint-John Allerdyce for Sabertooth to complete the bolt setup). As it stands, team 2 is rarely going to have the bolts for Cable's global, but he fits in much better with team 1's setup. This also makes team 1 half villains opening them up Captain America and giving them enough to have Scarlet Witch take out Namor on his lowest face.
Also, you should take Toad out completely and put in Cerebro instead. This removes the villain conflict and gives team 2 a very core setup of building up a wall and using either Captain America/Cerebro removal to clear a path, or using Namor to sneak damage through a full field. However, it is balanced since team 1 now has Cable and can use him to pull team 2's wall apart brick by brick. I would argue that subbing Vision in for X-23 would make the team more thematic, but it would also strip them of any possible early aggression and I think having that option is still useful.

Those are my thoughts on the balance and theming, but I'm sure that it should be fine however you end up dividing it. Best of luck with the event, I'm sure we're all looking forward to hearing about how it goes.